I like to use the details of the company, so if the placeholder is for a a phone number, I'd put the company phone number in as the placeholder. Same for email

I like to use the details of the company, so if the placeholder is for a a phone number, I'd put the company phone number in as the placeholder. Same for email etc. It's useful to see how you want the user to style the input, but with 'real' data not a '0000 0000-0000' kind of thing